The present invention relates to a multi device pick-up head and assembly process for use in, but not exclusively limited to, pick and place of very small display element(s) that need to be transferred from an initial substrate to a receiving substrate using a micro fluidic pick-up and transfer process.
To populate a display with very small light emitting diodes (LEDs), such as micro-LEDs, there may be a need to transfer the LEDs from the native substrate on which they have been manufactured to a target substrate that forms part of a display, or “display substrate.” Such small semiconductor devices may be assembled with a defined separation distance between them or closely packed together on the target substrate. Because of the small size of these devices (e.g., smaller than 49×40 μm), conventional pick and place techniques are unsuitable.
Vacuum pick-up, transfer printing, and electrostatic pick-up are some techniques that have been applied to the pickup and placement of small electronic devices. Each of these techniques has various drawbacks. For example, vacuum pick-up tools are typically limited to serial pick and place of individual devices. In another example, transfer printing uses direct contact (under high pressure) with the devices that are to be picked and placed, resulting in pick-up heads with limited work life or physical damage to the devices. In another example, the use of electrostatic forces to pick and transfer LED's can result in potential to damage electrostatic discharge (ESD) sensitive devices.